IEEE Power & Energy Magazine - January/February 2016 - 18

letters to the editor

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send comments to molken@ieee.org

READERS ARE ENCOURAGED TO
share their views on issues affecting
the electric power engineering profession. Send your letters to Mel Olken,
editor-in-chief, at molken@ieee.org.
Letters may be edited for publication.

PMUs Trump
1998 Ice Storm
The New York Power Authority (NYPA)
had the foresight to pursue state-of-theart research and development efforts,
led by Shalom Zelingher. One project
resulted in the successful installation
and use of the first phasor measurement units (PMUs) at Massena, Marcy,
and Moses substations. Arun Phadke
had developed these devices at Virginia
Tech. Measurements from the PMUs
were communicated to NYPA's New
York office, where I had the privilege
of working with exceptionally talented
engineers in the Operations Planning
Group (OPG). OPG improved stability
models by comparing PMU readings
with simulation results of actual system events.
The most dramatic application
of PMU readings occurred during
the ice storm of 1998. The storm resulted in over 3 in of ice collecting on
transmission cables and structures in
New York's North Country. Numerous forced outages and restorations of
facilities would have been challenging enough for system operators, but
these problems were compounded by
the occasional loss of several SCADA
Digital Object Identifier 10.1109/MPE.2015.2485903
Date of publication: 30 December 2015

ieee power & energy magazine

communication channels. Although the
entire state of the system was unknown, the PMUs sent readings to the
OPG, helping it to estimate the state
of the 115-kV system by combining
hand calculations, offline simulations,
and engineering judgment. OPG successfully provided guidance to system
operators, who successfully secured
the system and restored facilities in an
efficient manner. Even after some state
estimator functions were restored,
OPG simulation results proved closer
to reality as confirmed by the PMUs.
The ice storm of 1998 was my proudest moment as an engineer. The OPG
team applied nascent technology and
saved lives by improving the reliability
of electric service.
-Michael I. Henderson

The Proper LOLP
I read with great interest Dr. Billinton
and Dr. Chu's "History" column in the
July/August 2015 issue of IEEE Power
& Energy Magazine, "Early Evolution
of LOLP: Evaluating Generating Capacity Requirements." As a young engineer
(now retired), starting in 1967, I had the
good fortune of working at the General
Electric Company with one of the contributors they cite, Dr. L.K. Kirchmayer,
and his associate, Dr. L.L. Garver, who
was very instrumental in implementing
loss of load probability (LOLP) concepts in a practical manner. This was
especially true after the first great Northeast blackout, when the New York Power
Pool was formed and, among their accomplishments, they applied computerized

LOLP models to generation system expansion planning.
In the "History" article, it is pointed
out that an LOLP of one day in ten
years [or an loss of load expectation
(LOLE) of 0.1 days/year] was gravitated to fairly early on and has persisted to this day. Scant attention has
been given to explicitly factoring in
what the cost or benefit to power users
(and society in general) might be if
some other criterion and/or value was
chosen to help determine how much
installed load-serving capacity (both
supply and demand-side) is optimal.
In the last five decades the importance
of having reliable electric power has increased, as has the cost of outages. Simultaneously, the technical and regulatory terrain has also changed significantly.
Yet, the same reliability objective function target has endured as if the world had
remained static. Thus, the time has long
been ripe for engineers and policymakers
to start with a clean sheet and determine
what the proper LOLP/LOLE figure-ofmerit (and/or perhaps some other index)
should be today.
-Richard P. Felak

Author's Reply
We would like to thank Richard Felak for
his letter and his interest in our article.
In response, we would like to note
that considerable work has been done
on generating capacity reliability assessment since the early 1960s when
the LOLP criterion of 0.1 days/year was
established. This includes considerable
attention to the "cost or benefit to power
january/february 2016

Table of Contents for the Digital Edition of IEEE Power & Energy Magazine - January/February 2016